Telephone-exchange system.



A. B. SPERRY.

TELEPHONE EXCHANGE SYSTEM. APP LICATION FILED SEPT. 2, 1916.

1,92 L91 7 Patented Apr. 10, 191?.

lM veH/br Ar/haw' 5. spew y t in a group of finders.

ARTHUR B. SPERRY, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

change systems wherein calling lines are associated with idle connecting circuits by automatic finder switches. In such systems the finders are usually common to the groups,

1 and when a finder normally associated with a given group is being set from another group, it is necessary to remove the control of such finder from its group to prevent interference.

In accordance with this invention, this is accomplished by providing a means associated with each finder, which, when such finder is being set from another group than that to which it is normally allotted, renders I inoperative all the line relays of the group to which the finder belongs.

The invention will be. more readily understood when described with reference to the accompanying drawing, which shows only so much of a telephone exchange system as is necessary for a comprehension of I the invention. Each line is provided at the central office with a line relay l4 and a cutoif relay 15, and with multiple terminals 6, t, These multiples are adapted to be wiped over by a set of brushes 6, b, 6 one for each group of lines. Upon the initiation of a call, the finder brush shaft is given a primary movement under control of a magnet PM to position a set of brushes in operative relation to the calling group, and thereafter a secondary movement under control of the magnet SM to drive the brushes over such group in search of the calling line.

The invention will be clearly understood from a description of the operation.

Upon the removal of the receiver at. substation A, the following circuit is closed to energize the line relay 14: free pole of battery, resistance 10, left armature and back contact of slow relay 11 common to the group of lines to which substation A belongs, conductors 12 and 13, left wlnding of line relay 14, outer armature of cut-off re- Specification of Letters Patent.

Application filed September 2, 1916.

Patented Apr. 10, 1917.

Serial No. 118,250.

lay 15, line conductor 6, through the telephonic apparatus at substation A, line conductor 7 inner armature of cut-off relay 15, right winding of line relay 14 to ground. Assuming that the finder shown is the one allotted to the group to which substation A belongs, the commutator brush is in contact with commutator segment 21 of said group, and a set of brushes 5, Z), 6 is in operative relation to the group of terminals containing those of the calling line 6, if, F. The following circuit is therefore immediately closed, upon the energization of line relay 14, to pass the side switch into position 2 to initiate the secondary movement of the finder: free pole of battery, magnet PM, sideswitch arm 5 and its first contact, escape magnet 18, conductor 81, arm 3 and its first contact, conductors 40, 22, brush 20, segment 21, conductors 23, 24, 25 and 26 to ground at the right armature and front contact of relay 14. In position 2 the following circuit is closed for the secondary magnet SM to drive the brushes over the calling group: free pole ofbattery, magnet SM and its armature and back contact, arm 4' and its second contact, armature and back contacts of magnets 18 and RM, conductor 42, slow relay 11 to ground at the right armature and front contact of relay 16, which became energized when relay 14 attracted its right armature. In position 2, side-switch arms 5 and 2 connect the escapement magnet to the brush 6, over the armature and back contact of the testrelay 28. In passing over lines that are engaged in conversation, the escape magnet 18 cannot become energized, due to its circuit being opened by the relay 28 which is energized over the following circuits as such lines are encountered: free pole of battery, left winding of relay 28, conductors 29, 81, arm 3 and its second contact, brush N, terminal 25 of such lines to ground over the side-switch arms 3 and third contacts of the finders involved in such connections. This relay is maintained energized by its right winding as the brushes pass between terminals in order to prevent the grounded right armature of relay 16 from being extended to brush 5 and thus interferin g with existing connections. This circuit is as follows: free pole of battery, right windof magnets 18 and RM, conductor 42, relay 11, right armature of relay 16 to ground. When the calling line is reached, the following circuit is closed for the escapement magnet 18 to pass the side switch to position 3; free pole of battery, magnet SM, arm 5 and its second contact, magnet 18, conductors 31, 29, armature and back contact of relay 28, arm 2 and its second contact, brush m 6, terminal 5', conductors 32, 33 to ground at'the left armature and front contact of relay 14. The escape magnet 18, in energizing, passes the side switch into position 3. Arm 5, in passing out of position 2, opens the circuit of secondary magnet SM, thus stopping the finderwith the brushes 6, b, b in' engagement with calling line terminals t, t 7 Arm 3, in position 3, grounds multiple t to operate the cut-off relay 15, and causes this 20 line to test busy to other finders and conleading to the next finder.

Assume now that a line belonging to another group to which the relays 11, 16

are individual, initiates a call, and that the finder apportioned thereto is busy, and that the finder apportioned to the group to which 0 substation A belongs is the next idle finder.

T he energization of the line relay of such line, corresponding to 14, operates the relay 16 of such group, with the result that the following circuit is closed to initiate the primary movement of the finder: ground, right armature' and front contact of, relay 16, slow relay. 11, conductor 35, side-switch arm-36 and its third contact, conductor 37, right armature and'back contact of relay 16, slow relay 11, armatureand back contact of magnets RM and 18, side-switch arm 4 and its-first contact, armature and back contact 0f primarymagnet- PM, to free pole of battery. Slow relay 11, in attracting its left armature, removes the connection of'battery to all the line relays 14 of the group to which substation A belongs. Primary magnet PM makes and breaks the circuit traced until the commutator brush 20 reaches the commutator multiple segment of the calling group, when the following circuit is closed for the, escape magnet 18 to pass the side switch to position 2;free pole of battery, magnet PM, arm 5 and its first contact, magnet 18, conductor 31, arm 3 andits first contact, conductors 40, 22, brush 20, commutator multiple segment of the calling group corresponding to 21, conductors 23, 24, 25, 26, right armature and front contact of relay 14 of the calling line to ground. In position 2, the following circuit is closed for the secondary magnet SM to drive the brushes Z), 7), 6 over the terminals of the calling group; free pole of battery, magnet SM, its armature and back contact, arm 4 and its second contact, armatures and back contacts of magnets 18 and RM, slow relay 11, right armature and back contact of relay 16, con ductor 37, arm 36 and its third contact, conductor 35, relay 11, right armature and front contact of relay 16' to ground.

As hereinbefore described, in passing over lines that are engaged in conversation, the escapement magnet 18 cannot become energized, due to its circuit being opened by the relay 28, which is energized as such lines are encountered. When, however, the calling line is reached, the following circuit is closed for the escape magnet 18 to pass the side switch into position 3: free pole of battery, magnet SM, arm 5 and its second contact, magnet 18, conductors 31, 29, armature and back contact of relay 28, conductor 41, arm 2 and its second contact, brush 1), terminal t, conductors 32, 33, left armature and front contact of the line relay of the calling line to ground.

From this point on, the operation is the same as that already traced, the cut-off relay of the calling line being operated as the sideswitch arm 3 moves into position 3. This relay deenergizes the line relay, which in turn deenergizes slow relays 11 and 11. Relay 11, in retracting its left armature, restores the connection of battery to the line relays of the group to which substation A belongs, and relay 11 restores the connecti on of battery to the line relays of its group.

What is claimed is:

1. In a telephone exchange system, the

combination with a group of telephone lines, line relays therefor, an automatic finder switch apportioned to said group, driving means for said switch, means for rendering said driving means operative including the line relays of such group, a second group of lines, line relays therefor, means controlled by any of said line relays for actuating said driving means, and means operated when said finder is moving under control of a line in said second group for preventing the op eration of the line relays of the group to which said finder is apportioned.

2. In a telephone exchange system, the combination with a group of telephone lines, line relays therefor, a source of current with which said line relays are normally connected, an automatic finder switch apportioned to said group, driving means for said switch, means for rendering said driving means op- 1,221,917 llsil erative including the line relays of such group, a second group of lines, line relays therefor, means controlled by any of said line relays for actuating said driving means, and a relay operated when said finder is being set from said second group to remove the connection of said source of current from the line relays of the group to Which said finder is apportioned.

In Witness whereof, I hereunto subscribe my name this lst'day of September A. D., 1916.

ARTHUR B. SPERRY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

